Coarse and vernier roll position system for a rolling mill

ABSTRACT

The present disclosure relates to a rolling mill having an hydraulic piston cylinder assembly for adjusting the roll gap and includes a coarse position transducer arranged to measure the relative movement of the piston and cylinder of the assembly for passline adjustment of the lower work roll and a vernier position transducer arranged to also measure the relative movement of the piston and cylinder of the assembly for adjustment of the lower work roll for gauge control. A clamping device is provided for the vernier position transducer to allow it to be rendered operative and inoperative as the operation of the mill requires.

[ Dec. 1 0, 1974 Primary Examiner-Milton S. Mehr Attorney, Agent, or Firm-I-lenry C. Westin; Daniel Patch [57] ABSTRACT The present disclosure relates to a rolling mill having an hydraulic piston cylinder assembly for adjusting the COARSE AND VERNIER ROLL POSITION SYSTEM FOR A ROLLING MILL lnventor: Joseph Irwin Greenberger, Pittsburgh, Pa.

Wean United, Inc., Pittsburgh, Pa.

Filed: Mar. 6, 1974 United States Patent Greenberger [73] Assignee:

roll gap and includes a coarse position transducer arranged to measure the relative movement of the piston and cylinder of the assembly for passline adjustment of the lower work roll and a vernier position transducer arranged to also measure the relative movement of the piston and cylinder of the assembly for a ment of the lower work roll for gau 545 4B4 01 23 5 7 5mm 1W2 1 7 2 8 /3/ 2 2 7 7 .N 4 m 8 m n 8 M u m m a u n e m n s L f 1 0 D. M D. 3 A U'mF djustge control. A clamping device is provided for the vernier position transducer to allow it to be rendered operative and in- 32 operative as the operation of the mill requires. Fujino et 72/8 7 8 Claims, 4 Drawing Figures References Cited UNITED STATES PATENTS l2/l969 Stubbs et a1. 6/1970 Stone........;......

ROZL GAP GAUGE CONT ROL RANGE PA 55 L RA N65 PATENTED DEC 10 I974 SHEET 2 0F 2 COARSE AND VERNIER ROLL POSITION SYSTEM FOR A ROLLING MILL Present day rolling mills for rolling flat rolled products are usually equipped with hydraulic piston cylinder assemblies for positioning the work rolls for roll gap control. The most recent mills of this type include an electrical roll positioning control associated with the hydraulic piston cylinder assemblies for controlling the operation of the piston cylinder assemblies to maintain constant thickness rolled product even though the rolling force varies.

Because of the requirement in many mills that the lower work roll be maintained at more or less a fixed elevation, mills of the type being discussed provide some way of adjusting the bottom pair of rolls, if the mill is a four-high mill. In the so-called hydraulic mills this adjustment for passline has been done in some mills by operating the roll positioning hydraulic piston cylinder assemblies. Examples oftwo such designs are found in U.S. Pat. Nos. 3,7l3,314 and 3,757,553. In these patents there are illustrated mechanical means for repositioning the roll position indicating devices to maintain them in their narrow working ranges after the passline has been adjusted, for example, after the lower back-up and/or work rolls have been changed which have significant differences in diameters than the previous lower rolls removed from the mill.

The need to provide for such additional equipment not only adds to the initial expense and subsequent maintenance cost of the mill, but of equal importance requires valuable space in the window of the mill where space is at a premium. Moreover, such equipment complicates the design of the mill.

Accordingly, the present invention provides a simple, inexpensive, and trouble-free system for controlling the operation of long stroke roll positioning hydraulic piston cylinder assemblies of a mill for roll passline adjustment and for the roll gap control thereof.

More particularly, the present invention provides in a rolling mill having hydraulic piston cylinder assemblies for both adjusting the roll gap and passline separate means for controlling the piston cylinder assemblies movement for passline adjustment ofa roll or rolls of the mill and for controlling the roll gap to produce constant gauge.

Still more particularly, the present invention provides a coarse position transducer arranged to measure the large relative movement of the piston end cylinder of each piston'cylinder assembly for passline adjustment ofthe lower work roll and a vernier position transducer for measuring the relative small movement of the piston end cylinder of each piston cylinder assembly for adjustment of the lower work roll for a gauge control, including means for selectively bringing into operation one or the other of the different transducers depending on which operation the mill is performing.

These objects, as well as other novel features and advantages of the present invention, will be better appreciated when the following description of one embodiment thereof is read along with the accompanying drawings of which:

FIG. 1 is a partial, sectional elevational view of the bottom portion ofa four-high rolling mill incorporating the features of the present invention;

FIG. 2 is an enlarged elevational view of a portion of FIG. 1 illustrating the clamping device;

FIG. 3 is a sectional view taken on line 3-3 of FIG. 2, and

FIG. 4 is a sectional view taken on line 44 of FIG. 2.

In referring first to FIG. 1, it will be appreciated that the portion of the rolling mill not illustrated in the drawings follows well-known mill construction as can be seen from the aforesaid US. Pat. No. 3,757,553, in which the similarities of many of the parts shown in FIG. 1 of the present disclosure will be readily recognized, such as, for example, the construction of the lower part of the mill housing, the roll changing rails, and the roll positioning piston cylinder assembly.

The roll housing of the four-high mill shown in FIG.

1 is designated at 10, its window at 12, and its back-up I roll bearing chock at 14 and the roll positioning piston cylinder assembly at 16. According to usual rolling mill construction, the other housing assembly that makes up the mill stand is constructed similar to the one illustrated in FIG. 1. FIG. 1 also illustrates the rails 18 employed to change the back-up rolls of the mill.

In referring to the relatively long stroke roll positioning piston cylinder assembly 16, having say an 8 inch stroke, for the housing 10 as shown in FIG. 1, its cylinder 20 is inverted having its upper surface engageable with the bottom surface of the back-up bearing chock 14 through filler plates 22. The piston 24 of the piston cylinder assembly 16 is stationarily mounted within the window 12 of the housing. The piston cylinder assembly is designed to exert its entire force to lift the cylinder 20 upwardly. For lowering the cylinder 20, a pair of small piston cylinder assemblies 26 are provided being connected to the bottom of the cylinder 20 having their pistons 28 engageable with the bottom surface of the stationary piston 24 of the piston cylinder assembly 16.

As noted above, the present invention pertains to a system for controlling the movement of the piston cylinder assembly 16 so that a coarse and vernier adjustment can be accomplished thereof. In this regard, FIG. 1 illustrates the use of two separate pairs of position transducers, one pair for controlling a coarse adjustment of the piston cylinder assembly 16 arranged in a diametrically opposite manner and the other pair for controlling a vernier adjustment thereof similarly arranged. In FIG. I, legends have been provided indicating in somewhat exaggerated form the ranges of required coarse adjustment and vernier adjustment by the words passline range and roll gap gauge control range, respectively. The passline range can be of the order of 8 inches, whereas the roll gap range will be of the order 0.40 inch.

Describing first the coarse adjustment transducers, one of which is designated at 32 in FIG. 1, in which its housing 34 is secured to the adjacent surface of the cylinder 20 for movement therewith, the stem 36 of the transducer 32 is held stationary by a spring 38 located at the bottom of the assembly, the spring being received in a cap 42 secured to a bottom plate 44. The entire assembly is enclosed by a protective cover 46 which includes a bellows. While several well-known electrical transducers may be employed, the one illustrated is a linear variable differential transformer (LVDT) of the type 500 MP, having a range of 10 inches and a resolution of approximately 0.005 inch to 0.010 inch, manufactured and sold by Schaevitz Engineering of Pennsauken, N..I., U.S.A., and described in its Technical Bulletin AA-lb, copyright 1955. Within this range, the movement of the piston cylinder assembly 16 will be controlled to position the lower work roll at a desired passline elevation.

Describing now the transducers 50 provided for the vernier or fine control of the piston cylinder assembly 16, one of which is'shown in FIG. 1, this unit also is an LVDT similar to the unit 32, but of a type 200 MP having a range of 0.40 inch and a resolution of approximately 0.0002 inch to 0.0004 inch, manufactured and sold by the aforesaid Schaevitz Engineering. The housing 52 of the transducer 50 is stationarily mounted to the plate 44 through a housing 54. The stem 56 of the transducer 50 extends from below the housing 52 where it is biased in opposite directions by two springs 58 and 60 to the lower part of the cylinder 20. In this region, the stem 56 passes through a clamping device 62 employed to selectively secure the stem 56 to the cylinder for movement therewith. One of the clamping devices 62 is best shown in FIGS. 2, 3, and 4. It comprises a U-shaped spring having two leaf spring arms 64 and 66 having their base secured to a vertical plate 68 which is connected in turn to the adjacent wall of the cylinder 20. The spring arms 64 and 66 have gripper elements 70 and 72 which are urged tightly against the stem 56 by the agency ofa spring 74 carried by a bolt 76.

The free ends of the leaf spring arms 64 and 66 are provided with vertical wedges 78 and 80, the taper surfaces of which at identical points are engaged by a pair of rollers 82 and 84, respectively, The rollers are moved vertically against the wedges by a piston cylinder assembly 86 so that in the position shown in FIGS. 3 and 4, the rollers are in their lowest positions and the spring 74 has urged the gripper elements 70 and 72 into contact with the stem 56 of the transducer 50. When the rollers 82 and 84 are raised, the gripper elements 70 and 72 are forced apart to allow movement of the cylinder 20 relative to the stem 56.

In briefly describing the operation of the disclosed arrangement of the present invention, assuming first that one or more of the rolls have just been changed resulting in a need to raise the lower work roll and backup roll 4 inches, before the piston cylinder assembly 16 is operated by the main piston cylinder assembly control, not shown, the piston cylinder assemblies 86 are operated to free the stems 56 from the gripper elements 70 and 72 so that when the cylinder 20 moves, no movement will be imparted to the stems of the vernier transducers 50.

With the transducers 50 inoperative and their signal interrupted by an electrical operation of the main control, the control will activate the coarse transducers 32 so that they will measure the movement of the piston cylinder assembly 16. The piston cylinder assembly 16 will move the lower rolls upwardly, which movement will be measured by the coarse transducers 32 and from which measurement the piston cylinder assemblys operation will be interrupted when the transducer signals indicate that the rolls have been moved the required 4 inches. Since the passline position of the rolls is not extremely critical, the coarse and relatively the long main control and the vernier transducers 50 are rendered operational by a similar electrical operation. The piston cylinder assemblies 86 are operated to lower the rollers 82 and 84 to free the springs 64 and 66 and cause the stems 56 of the transducers 50 to be automatically gripped by the elements 70 and 72. The particular use of the piston cylinder assemblies 86 and the springs 74 assure that should a power failure occur to the piston cylinder assemblies 86 it will not affect the tie-in selectively established between the cylinder 20 and the stems 56 which rely totally on the force of the springs 74. Once these operations have been performed the mill will be ready to receive the material to be rolled.

The actual gap control system employed with the vernier transducers 50 may vary in form, the arrangement shown being intended to work with a system that measures the stretch of the mill as a function of the rolling pressure and produces a signal of the mill stretch which becomes at least a part of a gauge error or corrective signal used to control the operation of the piston cylinder assembly 16 to correct for the error and, hence, the change in gauge of the product being rolled. In this system, the vernier transducers will measure the movement of the cylinder 20 very accurately within its relatively narrow range and produce a signal representative thereof, which will be compared with the error signal until the error signal has been corrected. A gauge control system of this general type is more fully explained and illustrated in US. Pat. No. 3,496,743, that issued to M. D. Stone on Feb. 24, 1970.

In accordance with the provisions of the patent statutes, I have explained the principle and operation of my invention and have illustrated and described what I consider to represent the best embodiment thereof.

I claim:

1. In a rolling mill having an hydraulic piston cylinder assembly for positioning a roll of the mill to a coarse range control furnished by transducers 32 will very well serve this purpose.

When the piston cylinder assembly 16 is to be employed for roll gap control, the transducers 32 are ren- 'dered inoperative by an electrical operation of the working position and then positioning said roll in a vernier manner,

a first means for measuring the relative movement between the piston and cylinder of said piston cylinder assembly when said piston cylinder assembly is employed to position said roll to the coarse working position, and

a second means for measuring the relative movement between the piston and cylinder of said piston cylinder assembly when said piston cylinder assembly is employed to position said roll in the vernier man ner.

2. In a rolling mill having a relatively long stroke hydraulic piston cylinder assembly for both positioning the lower working roll of the mill for passline location and for adjusting the roll gap of the mill for gauge control,

a first means for measuring the relative movement between the piston and cylinder of said piston cylinder assembly when said piston cylinder assembly is employed for passline positioning, and

a second means for measuring the relative movement between the piston and cylinder of said piston cylinder assembly when said piston cylinder assembly is employed for adjusting the roll gap for gauge control.

3. In a rolling mill according to claim 2, wherein said first means comprises an electrical position transducer having a relatively wide range of measurement and relatively coarse resolution, and wherein said second means comprising an electrical position transducer having a relatively narrow range of measurement and relatively fine resolution.

4. In a rolling mill according to claim 3, wherein said coarse position transducer comprises a linear variable differential transformer having a wide range of the order of 8 inches and a resolution of the order of approximately 0.005 inch to 0.010 inch, and

wherein said fine position transducer comprises a linear variable differential transformer having a narrow range of the order of 0.40 inch and a resolution of the order of approximately 0.0002 to 0.0004 inch.

5. In a rolling mill according to claim 3, including means for securing either one or the other of said coarse or fine position transducers to said piston cylinder assembly in a manner to measure its movement, and

other means for selectively connecting the other of said coarse or fine position transducers to said piston cylinder assembly in a manner to measure its movement.

6. In a rolling mill according to claim 5, wherein said power means adapted to displace said wedge means to separate said gripper means and free said stem of said fine measuring transducer from said gripper means.

8. In a rolling mill according to claim 6, wherein said stem member of said fine measuring transducer is movably mounted, and

yieldable means associated with said movable stem member for maintaining said movable stem member in a preselected position relative to a nonmoving part of said fine measuring transducer. l l l 

1. In a rolling mill having an hydraulic piston cylinder assembly for positioning a roll of the mill to a coarse working position and then positioning said roll in a vernier manner, a first means for measuring the relative movement between the piston and cylinder of said piston cylinder assembly when said piston cylinder assembly is employed to position said roll to the coarse working position, and a second means for measuring the relative movement between the piston and cylinder of said piston cylinder assembly when said piston cylinder assembly is employed to position said roll in the vernier manner.
 2. In a rolling mill having a relatively long stroke hydraulic piston cylinder assembly for both positioning the lower working roll of the mill for passline location and for adjusting the roll gap of the mill for gauge control, a first means for measuring the relative movement between the piston and cylinder of said piston cylinder assembly when said piston cylinder assembly is employed for passline positioning, and a second means for measuring the relative movement between the piston and cylinder of said piston cylinder assembly when said piston cylinder assembly is employed for adjusting the roll gap for gauge control.
 3. In a rolling mill according to claim 2, wherein said first means comprises an electrical position transducer having a relatively wide range of measurement and relatively coarse resolution, and wherein said second means comprising an electrical position transducer having a relatively narrow range of measurement and relatively fine resolution.
 4. In a rolling mill according to claim 3, wherein said coarse position transducer comprises a linear variable differential transformer having a wide range of the order of 8 inches and a resolution of the order of approximately 0.005 inch to 0.010 inch, and wherein said fine position transducer comprises a linear variable differential transformer having a narrow range of the order of 0.40 inch and a resolution of the order of approximately 0.0002 to 0.0004 inch.
 5. In a rolling mill according to claim 3, including means for securing either one or the other of said coarse or fine position transducers to said piston cylinder assembly in a manner to measure its movement, and other means for selectively connecting the other of said coarse or fine position transducers to said piston cylinder assembly in a manner to measure its movement.
 6. In a rolling mill according to claim 5, wherein said position transducers include stem members, said means for selectively connecting said one transducer to said piston cylinder assembly being associated with said fine measuring transducer, and said selective connecting means comprising a gripper means for selectively engaging the stem of said fine measuring transducer.
 7. In a rolling mill according to claim 6, wherein said gripper means includes a spring means for continuously urging said gripper means into engagement with said stem of said fine measuring transducer, wedge means associated with said gripper means, and power means adapted to displace said wedge means to separate said gripper means and free said stem of said fine measuring transducer from said gripper means.
 8. In a rolling mill according to claim 6, wherein said stem member of said fine measuring transducer is movably mounted, and yieldable means associated with said movable stem member for maintaining said movable stem member in a preselected position relative to a non-moving part of said fine measuring transducer. 